Fix "unused attribute" build error.

This reverts parts of
82ea128f190dbe8d707cb140a5a2bb2b48bef58d
e1309004099d1a1c0a9bc1ba6de9e5054629da3c
which were a bit over-zealous at removing "unused" stuff. LGPLv3+/MPL

svtools/inc/svtools/txtattr.hxx

@@ -59,7 +59,9 @@ public:
 
     virtual                 ~TextAttrib();
 
-    sal_uInt16                  Which() const   { return mnWhich; }
+    sal_uInt16              Which() const   { return mnWhich; }
+    virtual void            SetFont( Font& rFont ) const = 0;
+    virtual TextAttrib*     Clone() const = 0;
 
     virtual int             operator==( const TextAttrib& rAttr ) const = 0;
     int                     operator!=( const TextAttrib& rAttr ) const

svtools/source/edit/textdoc.cxx

@@ -54,14 +54,14 @@ int SAL_CALL CompareStart( const void* pFirst, const void* pSecond )
 // -------------------------------------------------------------------------
 TextCharAttrib::TextCharAttrib( const TextAttrib& /* rAttr */, sal_uInt16 nStart, sal_uInt16 nEnd )
 {
-    mpAttr = NULL;
+    mpAttr = rAttr.Clone();
     mnStart = nStart,
     mnEnd = nEnd;
 }
 
 TextCharAttrib::TextCharAttrib( const TextCharAttrib& rTextCharAttrib )
 {
-    mpAttr = NULL;
+    mpAttr = rTextCharAttrib.GetAttr().Clone();
     mnStart = rTextCharAttrib.mnStart;
     mnEnd = rTextCharAttrib.mnEnd;
 }